In silver halide photographic materials, photographic emulsion layers or other layers are often colored to allow light in a specific wavelength region to be absorbed.
Generally, a colored layer is provided between a photographic emulsion layer and a support or on the surface side of the support which is opposite to the photographic emulsion layer, to prevent fuzziness. That is, the colored layer prevents halation from being caused by light that is scattered when incident light is passed through photographic emulsion layers or after incident light is transmitted through it. The light is reflected at the interface between the emulsion layer and the support, or reflected on the surface which is opposite to the emulsion layer, and the reflected light enters the photographic emulsion layers again. Such a colored layer is called an antihalation layer.
In X-ray photographic materials, a colored layer, which functions as a crossover cut filter, is sometimes provided to improve sharpness by reducing crossover light.
The layers to be colored generally comprise a hydrophilic colloid. Dyes are generally incorporated into the layers to color them. It is necessary that the dyes meet the following requirements.
(1) The dyes have proper spectral absorption according to the intended use. PA1 (2) The dyes are inactive photographically and chemically. Specifically, the dyes do not have any adverse effect on the performance of silver halide photographic emulsion layers in a chemical sense. For example, they do not cause a lowering in sensitivity, a degradation of latent images or fogging. PA1 (3) The dyes are decolorized or removed by dissolution during the course of development so that no harmful color is left on the photographic materials after processing.
However, when the colored layer such as the antihalation layer or the crossover cut layer is formed by using a hydrophilic colloid, there is a disadvantage in that the volume of the water-permeable layers is increased and, as a result, drying characteristics during development are deteriorated.
In order to solve this problem, a dye is fixed to a layer, which is used to improve the adhesion between the hydrophilic colloid layer and the support. (The layer which plays a role in bonding the support to the hydrophilic colloid layer is referred to herein as the undercoat layer.) Methods for fixing dyes into the undercoat layer include a method wherein a dye is allowed to be adsorbed by a mordant as described in U.S. Pat. Nos. 4,957,856 and 4,965,180 and Japanese Patent Application No. 62-224447, a method wherein a dye dissolved in oil as oil droplets is emulsified and dispersed as described in Japanese Patent Application No. 1-142688, a method wherein a dye is adsorbed on the surface of an inorganic material as described in Japanese Patent Application No. 1-139691, a method wherein a dye is adsorbed by a polymer as described in Japanese Patent Application No. 1-119851 and a method wherein a dye in the form of a solid is dispersed as described in U.S. Pat. Nos. 4,803,150 and 4,900,652 and Japanese Patent Application No. 1-87367.
It is disclosed in the examples of these patent specifications that an undercoating polymer layer used for the undercoat layer and a dye layer are coated so as to be brought into contact with each other. Such a coating has a disadvantage in that the dye is introduced into the undercoating polymer and is left as a residual color after development.
It is believed that the dye enters into the gaps of the undercoating polymer and is confined in the polymer during the drying of the dye layer, whereby the residual color is formed.